Crossfire is running two AMD/ATI video cards, Raid is using an array of hard drives that work together putting it in a simple way of explaining it. As for the crossfire, If it is only cross fire and not SLI then it will only work with 2 cards if there AMD/ATI Nvidia using 2 cards is called SLI. What board are you looking at so we can more easily see what it supports.

Nope won't work, The i7 isn't needed for gaming either, i5 will work just as well, On the I5/i7 the ones with the K at the end are unlocked for overclocking and you'll need the Z87 motherboard to over clock but with the speed of these chips over clocking isn't needed at all other than running bench marks, So the Save $100 get the i5 4670K and put the money towed a Z87 motherboard if you want to overclock, If not OC ing then save a little more and just get the i5 4670 and a MB that supports SLI so you can run both your GTX760's I'm posting from my phone so searching a good MB is tough but will do it after I get out of work tonight and I'm sure others will suggest some good boards, PPMguire is a hardware master on this forum and I'm sure he will have some good suggestions.

SLI is what the call using 2 Nvidia video cards, If your putting in 2 x GTX 760's then you will be running SLI If your not over clocking and want the I7 just get the i7 4770 without the K at the end and it will be a little cheaper